The Arcanum of radiance allows a mage to tap into the holy light of the upper planes, producing blinding flashes and beams that sear flesh and soul alike. This arcanum is unique, in that it is most often learned through divine inspiration when a deity chooses a mortal to act on their behalf. Unlike traditional magical education, this borrowed power is imbued into the chosen, along with the knowledge to wield it. Of course, it can be taken away as easily as it is given. At the end of ones service, the power withdraws, as the gods do not want their plans disrupted by unexpected agents. In the event that the chosen breaks their covenant with their deity, this power will leave far more violently.
The most vital feature of this arcanum is its extreme effectiveness against both fiends and undead, the enemies of the Upper Planes, who the chosen are charged with destroying on sight. Many chosen are called specifically to eliminate such creatures who are encroaching on the Divine's holy sites. There is one order with a far greater goal. The Reaping Templars are known for their terrifying mastery of radiance and tireless war against every undead, with spells like The Grave King's Luminous Scythe, which is able to instantly destroy any undead before the caster.